The discovery was made by conducting tests on mice with two human genes, PER1 and its partner PER2, which has previously been linked to sleep disturbances.

When PER2 was defective in the mice, as expected they dozed off earlier than usual. But de-activating PER1 affected eating behaviour, leading to mice wanting to eat when they should be sleeping.

"For a long time, people discounted night eating syndrome as not real," said lead scientist Dr Satchidananda Panda, from the Salk Institute in La Jolla, California.

"These results in mice suggest that it could actually be a genetic basis for the syndrome.

"We really never expected that we would be able to decouple the sleep-wake cycle and the eating cycle, especially with a simple mutation. It opens up a whole lot of future questions about how these cycles are regulated."

When the researchers restricted access to food, offering it to the mice only at normal meal times, they found that even animals with the faulty PER1 gene maintained a normal weight.

Over a 10-week period their weight was no different to that of animals with functioning PER1 genes. This showed that the weight gain caused by faulty PER1 was entirely due to meal mistiming and not other metabolic factors.

The scientists believe that normally, PER1 and PER2 are kept synchronised and turned on and off at the same time, keeping sleep and eating cycles aligned. But a mutation in PER1 can break this link, leading to an urge to eat at night.

Also on The Huffington Post

Cherries (particularly tart cherries) naturally boost levels of melatonin (naturally occurring hormone that helps regulate the sleep cycle), so try having a glass of cherry juice before hitting the hay.

Walnuts are a good source of tryptophan, a sleep-enhancing amino acid that helps make serotonin and melatonin, the “body clock” hormone that sets your sleep-wake cycles, according to NHS website.

Most oily fish (especially tuna and salmon) boast vitamin B6, which is needed to make melatonin, so a nice tuna salad or salmon dish could just make your sleepy time that much better.

Almonds are rich in magnesium, a mineral needed for quality sleep and they're fun to snack on. Try mixing them with some dried fruits to add flavour.

Drinking this herbal tea will help you get your snooze on faster, as it lacks the caffeine most teas have and is associated with an increase of glycine, a chemical that relaxes nerves and muscles.

Try adding honey to your tea before bed time. It contains natural sugar that slightly raises insulin levels and allows tryptophan (an amino-acid that makes us sleepy) to enter the brain more easily.

The snack combines two components for getting some snooze: carbohydrates from the cereal and calcium from the milk. Yum! (Perhaps it could explain why we're still so sleepy after breakfast at times.)

Our favourite tropical fruit is an excellent source of magnesium and potassium, which help relax muscles. They also contain tryptophan, which convert to serotonin (sleep-inducing neurotransmitter) and melatonin.

White rice (in particular jasmine rice) has a high glycemic index (glycemic index (GI) is a measurement carried out on carbohydrate-containing foods and their impact on our blood sugar), so eating it will significantly reduce the time it takes you to fall asleep.

Kale is not only good for your health and diet, but will help you get your beauty sleep. Loaded with calcium, green leafy vegetables help the brain use tryptophan to manufacture melatonin and serotonin - while keeping your diet in check.

Cheese and crackers may just be your best bedtime snack choice. Calcium (found in cheese, yogurt and milk) helps the brain use the tryptophan found in dairy to manufacture sleep-triggering melatonin. Plus it's delicious.

Hummus (as well as chickpeas) is a great source of tryptophan, so some hummus with whole-grain crackers could save you from some serious tossing and turning.